Fluid actuated suspension device for vehicles, aircraft, and the like



Sept, 5, 1950 w. w. MARsToN 2,521,074

FLUID ACIUATED SUSPENSION DEVICE FCR VEHICLES, AIRCRAFT, AND' THE LIKE Filed Feb. .24. 1948 IH Il |I l I |v l l III I l l l l l'i l IIIHI |I In VPatented Sept. 5, 1950 FLUID ACTUATED SUSPENSION DEVICE FOR VEHICLES, AIRCRAFT, AND IHE LIKE Walter Wilson Marston, Wednesield, England Application February Z4, 1948, Serial No. 10,438 In Great Britain August 16, 1946 7 Claims. l

This invention relates to lshock absorbing suspension devices of the fluid actuated type for vehicles, aircraft and the like of the kind embodying a pair ci telescopic members connected between the wheel mounting or equivalent and the vehicle chassis or equivalent to define a working space or spaces of variable volume occupied by a hydraulic fluid so that relative movement of the telescopic members in one direction causes an increase of pressure in the hydraulic fluid which pressure is in turn transmitted by the said hydraulic iluid to a compressible fluid separated by movable means from the hydraulic fluid, said compressible fluid acting as a-,Spring and adapted to resiliently oppose movement to the telescopic members in said direction.

The object of the present invention is to provide an improved construction of suspension device of the specified type wherein movement of the telescopic members in either direction is resiliently opposed by a compressible fluid. f

The present invention is characterized by the compressible fluid being disposed in two containers one of which is acted upon by hydraulic fluid from one Working space of the telescopic pair, whilst the other container is acted upon by hydraulic fluid from a second working space, of the telescopic pair, so that relative movement in either direction of the telescopic members will cause the hydraulic fluid to act upon the compressible fluid in one or other of the containers to compress the fluid therein causing saidcompressible fluid to act as springs to resiliently oppose the relative movement of the telescopic pair.

In the accompanying drawing there is shown in section a suspension device according to the present invention.

Referring to the drawing the telescopic pair comprises a hollow piston I closed 'at its lower end and adapted to be connected at said end to a wheel mounting or the like, and a cylinder 2 Which is located within a cylindrical housing 3 said cylindrical housing being screwed into a head 4. v v

Bolted to the head 4 is a closed cylindrical container 5 provided with a fluid tight partition 6 to define uppel` and lower chambers 1, 8, in which are located inflatable rubber air bags 9, I0.

Therubbel` bags 9, I are of annular form and surround a conduit II extending from the head 4 to the bottom of the container 5. Each bag is provided with a suitable valve I2 extending through the wall of the container to enable the bags to be readily inflated to the desired pressure as required.

The head 4 and container 5 are mounted on the vehicle chassis or'equivalent in any suitable manner. The cylindrical housing 3 is provided at its lower end with a bushing I3 to form a bearing for the piston I to slide therein and also provided with sealing means I4 and a closure member I5.

The hollow piston I is provided with an enlarged head I6 to enable it to be a sealing fit inthe cylinder 2 and, except as hereinafter described, form a seal between the upper working space I1 and the lower annular working space I8. A tubular extension I9 from the head 4 extendsdownwardly therefrom and passes through an opening 20 in the piston I into the hollow interior of the latter. f

The tubular extension I9 and conduit II are connected by a duct 2I in the head 4 said duct communicating with .an opening 22 normally closed by a plug23 for the purpose of lling the suspension device with hydraulic fluid.

I -The operation of the suspension device according to the present invention is as follows, assuming upward movement of the piston I due to the wheel or wheels of the vehicle associated therewith being subject to a road shock or the like the upper working space I'I is reduced in volume and hence pressure applied to the hydraulic fluid. Thus hydraulic fluid is caused to enter the already full piston I through the opening 26 in the head I6 thereof causing fluid to be forced under pressure up the tubular extension I9 which fluid movement is conveyed along the duct 2| to the conduit I I.

, rlfhe conduit II is closed at its lower end and that part of it in the lower chamber 8 is perforated to permit hydraulic iluid to enter said chamber and compress the inflated rubber bag III.

Thus the hydraulic fluid transmits the pressure created therein due to upward movement of the piston I, to the air bag lvwhich latter functions as'an air spring resiliently opposing the movement of the piston l and effecting absorption of the road shock or the like,

Due to its inherent resiliency the air bag Ill tends to return to its normal volume reversing the movement of the hydraulic fluid which causes the piston I to be returned to its normal position, said position being determined by the load on the vehicle or the like at any given instarrt.

In' order to resiliently oppose motion of the piston I in the opposite direction due to rebound from the .above described movement, or when the wheel or wheels encounter a road depression or the like, the lower working space i8 is reduced in volume and applies pressure to the hydraulic fluid causing same to pass through the clearance 24 between the bottom of the cylinder 2 and the upper sealing means I4 into the annular chamber 25 formed between said cylinder 2 and the cylindrical housing 3.

Owing to the annular. chamber: 25` beingv al# ready filled with hydraulic fluid some ofsaid4 fluid`` is forced under pressure through the short duct 26 in the head 4 to a small annular chamber 21'! communicating with the upper. chamber 1 where. in the fluid is Ipermitted to pass' through a; per-A forated sleeve 28 and compress the inflated rubber bag 9.

Thus in a similar manner to fthatfhereinbefore.: described with reference to the air bag'l resili-. ently opposing upward movement of the piston I, downward movement thereof is resiliently op=- posed by the air bag 9'ldue to transmission of pressure thereto by the hydraulic.' fluidi Afs` irrthe case of the perforations of the: coneduit I-I perforations ofthe sleeve 28l causefthef hydraulic fluid pressure to'be'evenly appliedto theair bags* `9,' l0? preventingf the latter4 being'v subject to localised high pressure.

In order to damp the motion of the piston" in either direction theopening 2D'in the pistonhead IS-isftapered internally to a point 201 of minimum bore. The tubular extension IS is'tapered externa-ily from a point |91`of minimum diameter'v neith'er direction. Thus as the piston-is moved in4k either directionV the effective opening in the piston' head I5 is reduced and due to the throttling-of the hydraul'i'cfluid Ipassing therethrough' into or out of the piston interiore.I damping"efi feet on the motion of the'latter is created.

It will be appreciated from the foregoingthat the' tendency ofthey device is to restore thepiston tof aneutral position, which position: is indicated in the drawing. In order to ensure hydraulic fluid pressure equalization at this neutral posi-l tion the two working'spaces l1, I8, are' communicated bymeans of one or more groovesl129in the wall of the' cylinder 2 said groove or grooves being'of alength in' excess of theV length ofthe piston head I6"1 It is to be understood that when the suspension device is charged .with hydraulic fluid, due tothe groove 29 the hydraulic fluid pressure. on each side. ofthe piston head I6' is equal although-the device is. supportingA the weight of the vehicle over the wheel or axle with which the device is associated. The. reason that vthe vehicle is supportedv is due to the fact that a greater areaof piston head IS is presented to the hydraulicfluid' of'working space l-T than to thehydraulic.. fluid of. Working spa-ce I8'. However upon the vehicle beingY loaded a pressuredifference.. is created.

The provision of the said grooveI orvv groovesl also permits all the various working spaces, chambers, ducts, and thelike ofthe suspension device to be charged with hydraulicv iluidfrorn the. opening. 22.

The usual. telescopic. shields 30` are provided toprotect the. telescopic members;

Iclai-m:

l. A fluid actuated suspension device for-supportingg. wheel axle `from a vehicleT-comprisinga piston adapted for connection to a vehicle wheel axle; a cylinder adapted for mounting on` the vehicle in'which cyli-nderl the -piston slides Ato define. two working spaces for hydraulic fluidtheresaid Working spaces at a predetermined position only of said piston in the cylinder; a container mounted with said cylinder, said container having two `chambers therein for hydraulic fluid; a. member having ducts connecting said cylinder with said container and effecting hydraulic fluid communication between each working space and acorresponding chamber; and movable members in@ each of saidA chambers adapted to separate the hydraulic fluid from compressible fluid in said chambers for resiliently accommodating pressure variations-.inthe hydraulic fluid due to relative movementl of the piston and cylinder.

2. A fluid actuated suspension device for supporting a wheel' axle from a Vehicle comprising a. piston adapted. for connection to a vehicle Wheelfaxle;V a? cylinder adapted for mounting on the vehicle in which cylinder the piston slides to define two Working spaces for hydraulic fluid therein, said cylinder having a duct to communicate said workingspaces at a predetermined position only'of'said pistonfin the cylinder; a con.- tainer` mountedf with said cylinder, saidt con'- tainer'havingrtwochambers therein for hydraulic fluid; amember having ducts connecting' said? cylinder'- with said container and effecting hy; draulic fluid communication: between each work'- ing' lspace and 'a corresponding chamber; and septarateinatable 'air' bagsdisposed' in each of'said chambers adapted to resiliently accommodate pressure variations `thereon by the. hydraulic fluid. dueto relative movement of the piston andcyl'- inder'.

3'. An improved fluid actuated' suspension de; vicerfor supporting-a wheel axle from avehicle'; comprising a piston adaptedfor connectionttoa vehicleiwheel axl'e,'. said' piston having a head" at e'a'chuend', said heads beingY of different effective area; a cylinder'adapted for mountingV orr the vehiclev andin which cylinder the piston slides to define two working spaces therein for'. hy.- drauli'c fluidga:V greater area. of piston head'being. presented to'one'workingspace than the other. fior supporting the vehicleV weight over the wheel axle, said cylinder hayingfa duetto-'communicate said' Workingspacest ata predetermined position only of said piston in the cylinder;` a container mpunted'with said cylinder, said` container hav-1 ing" two chambers: therein. for hydraulic' fluid; a member having ducts connecting said cylinder with: said container-"and effecting hydraulicfluid communication' betweeneacb. working spaceand ai'correspon'ding chamber; and separate-inll'atable air.' bags disposed in. each' of said' chambers adapted' to resiliently accommodate pressure variations thereon-by the hydraulic fluid due to relative movement ofthe pistonta-nd cylinder.y

An: improvedlfluidy actuated suspension. device'wforr'supporting a wheel axle from a vehicle;

0 comprising a piston adapted for connection to'fa vehicle'wheel axle; a. cylinderr adapted for mount ing.- on` the Vehicle in whichV cylindery the piston slides toi-definetwoy Work-ing spaces therein, said cylinder having a duct to communicate said work-Y ingl spaces atta: predetermined 'position only;r of

imsaid.- cylinder having,r a-duct tocommunicate adapted to reslently aCCOmmOdate Pressure variations thereon by the hydraulic fluid due to relative movement of the piston and cylinder.

5. An improved fluid actuated suspension device for supporting a wheel axle from a Vehicle, comprising a piston adapted for connection to a vehicle wheel axle, s-aid piston being hollow and having an open end; a cylinder adapted for mounting on the vehicle and in which cylinder the piston slides to dene two working spaces therein, said cylinder having a duct to communicate said working spaces at a predetermined position only of said piston in the cylinder; a container mounted with said cylinder; a hydraulic fluid tight partition to said container to define therein two chambers for hydraulic fluid; a head member having ducts connecting said cylinder with said container and eiecting hydraulic iiuid communication between each working space and a corresponding chamber; separate inflatable air bags disposed in each of said chambers adapted to resiliently accommodate pressure variations thereon by the hydraulic fluid due to relative movement of the piston and cylinder; and a tapered member fixed within the cylinder and extending within the hollow piston and adapted for throttling a flow of uid between same and said piston to effect further damping of the relative motion of the piston and cylinder.

6. An improved fluid actuated suspension device for supporting a wheel axle from a vehicle, comprising a piston adapted for connection to a vehicle wheel axle, said piston having a head at each end, said heads being of different effective area; a cylinder adapted for mounting on the vehicle and in which cylinder the piston slides to define two working spaces therein for hydraulic uid, a greater area of piston head being presented to one working space than the other for supporting the vehicle weight over the wheel axle, said cylinder having a duct to communicate said working spaces at a predetermined position only of said piston in the cylinder; a container mounted with said cylinder; a hydraulic fluid tight partition to said container to define therein two chambers for hydraulic fluid; a head member having ducts connecting said cylinder with said container and effecting hydraulic uid communication between each working space and a corresponding chamber; and separate inatable air bags disposed in each of said chambers adapted to resiliently accommodate pressure variations thereon by the hydraulic fluid due to relative movement of the Ipiston and cylinder.

7. An improved iluid actuated suspension device for supporting a wheel axle from a vehicle, comprising a piston adapted for connection to a vehicle wheel axle, said piston being hollow and having an open end and also having a head at each end, said heads being of different effective area; a cylinder adapted for mounting on the vehicle and in which cylinder a piston slides to dei-lne two working spaces therein for hydraulic fluid, a greater area of piston head being presented to one working space than the other for supporting the vehicle weight over the wheel axle, said cylinder having a duct to communicate said working spaces at a predetermined position only of said piston in the cylinder; a container mounted with said cylinder; a hydraulic fluid tight partition to said container to denne therein two chambers for hydraulic uid; a head member having ducts connecting said cylinder with said container and effecting hydraulic fluid communication between each working space and a corresponding chamber; separate inflatable air bags disposed in each of said chambers adapted to resiliently accommodate pressure variations thereon by the hydraulic iiuid due to relative movement of the piston and cylinder; and a tapered member fixed within the cylinder and extending within the hollow piston and adapted for throttling a iiow of fluid between same and said piston to effect further damping of the relative motion of the piston and cylinder.

WALTER WILSON MARSTON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATEN'I'S Number Name Date 1,936,788 Hardy Nov, 28, 1933 2,165,465 Ehrhardt et al July 11, 1939 2,451,171 Mullen Oct. 12, 1948 

